Method for receiving broadcasting signal and broadcasting receiver

ABSTRACT

A method for receiving a broadcasting signal and a broadcasting signal receiver are disclosed. Even when a cell is changed while an emergency alert is output, the emergency alert can be continuously output using emergency alert table information included in the broadcasting signal and channel information of the cell. The emergency alert table information may include a cell identifier and the channel information of the cell may include virtual channel information of the cell.

CROSS-REFERENCES TO RELATED APPLICATIONS

The present application is a reissue application of U.S. Pat. No.8,458,752 B2, issued from U.S. application Ser. No. 13/104,782, filedMay 10, 2011, which is a continuation of U.S. patent Application Ser.No. 12/728,156, filed on Mar. 19, 2010, now U.S. Pat. No. 7,966,633,which is a continuation of U.S. patent application Ser. No. 12/035,261,filed on Feb. 21, 2008, now U.S. Pat. No. 7,793,320, which claims thebenefit of earlier filing date and right of priority to KoreanApplication No. 10-2007-0018592, filed on Feb. 23, 2007, and claimspriority to U.S. Provisional Application Nos. 60/911,510, filed on Apr.12, 2007, and 60/947,984, filed on Jul. 4, 2007, the contents of all ofwhich are hereby incorporated by reference herein in their entirety.

BACKGROUND

1. Field of the Disclosure

The present disclosure relates to a method for receiving a broadcastingsignal and a broadcasting receiver.

2. Discussion of the Related Art

As digital broadcasting technologies have been developed, a user canreceive various additional services as well as a broadcasting signalsuch as a video/audio signal. A digital broadcasting signal istransmitted through satellite, cable, terrestrial and Internet networksand is provided to the user. A digital broadcasting receiver can receivethe digital broadcasting signal and provide various additional servicesas well as the video/audio signal to the user.

Recently, a natural disaster such as an earthquake or a flood or anemergency such as a terrorist threat or an incendiary fire increasinglyoccurs. The damage degree of the terrorist threat or the naturaldisaster due to environmental pollution is increased and the rippleeffect thereof is also increased.

When such an emergency occurs, an emergency alert message may beincluded in a broadcasting signal and may be provided to the user. Theuser can obtain information on the emergency through the emergency alertmessage while viewing a broadcasting program. A broadcasting receiverfor receiving a broadcasting signal including additional services suchas the emergency alert message or a video signal may include a fixedbroadcasting receiver for receiving the broadcasting signal withoutmovement thereof and a mobile broadcasting receiver for receiving thebroadcasting signal while moving.

Unlike the fixed broadcasting receiver, the mobile broadcasting receivershould continuously output the service such as the emergency alertmessage included in the received broadcasting signal.

SUMMARY OF THE INVENTION

Accordingly, the present invention is directed to a method for receivinga broadcasting signal and a broadcasting receiver that substantiallyobviate one or more problems due to limitations and disadvantages of therelated art.

An object of the present invention is to provide a method for receivinga broadcasting signal and a broadcasting receiver for receiving thebroadcasting signal, which are capable of continuously providing aservice such as an emergency alert message while moving.

Additional advantages, objects, and features of the invention will beset forth in part in the description which follows and in part willbecome apparent to those having ordinary skill in the art uponexamination of the following or may be learned from practice of theinvention. The objectives and other advantages of the invention may berealized and attained by the structure particularly pointed out in thewritten description and claims hereof as well as the appended drawings.

To achieve these objects and other advantages and in accordance with thepurpose of the invention, as embodied and broadly described herein, amethod for receiving a broadcasting signal includes receiving emergencyalert table information describing an emergency alert message andchannel information of a cell from the broadcasting signal received froma first channel of a first cell which is a transmission area of thebroadcasting signal. The emergency alert message is output using thereceived emergency alert table information. When handing over from thefirst cell to a second cell, an identifier of the second cell isobtained and the emergency alert message, which has been output from thefirst cell, is continuously output from the second cell using thechannel information of the cell.

In another aspect of the present invention, a broadcasting signalreceiver includes a tuner configured to tune into a broadcasting signaltransmitted by a first cell, a demodulator configured to demodulate thetuned broadcasting signal, a demultiplexer configured to demultiplex thedemodulated broadcasting signal, a program table information decoderconfigured to parse an emergency alert table in the demultiplexedbroadcasting signal, a decoder configured to decode an audio/videosignal in the broadcasting signal parsed by the demultiplexer, an outputunit configured to output the broadcasting signal decoded by the decoderand a controller configured to control an emergency alert to be outputusing information obtained from the emergency alert table in thebroadcasting signal of the first cell and controls the emergency alertto be continuously output even when handing over from the first cell toa second cell.

The emergency alert table information may include the identifier of thecell. The emergency alert table information may include at least one ofvirtual channel information for transmitting the emergency alertmessage, carrier frequency information, information on a program numberof a channel for transmitting the emergency alert, and transport streamidentifier.

The channel information of the cell may be obtained from tableinformation including virtual channel information of the identifier ofthe cell.

The identifier of the second cell may be obtained from any one of amaster guide table (MGT) of the received broadcasting signal, theemergency alert table information and signaling information of thereceived broadcasting signal. The emergency alert table information mayinclude a field for reporting priority of the alert.

The controller may control the tuner to tune the channel to a channelfor transmitting the same broadcasting contents as broadcasting contentsoutput from the first channel of the first cell, among channels of thesecond cell, using the channel information of the cell, if the output ofthe emergency alert message is finished.

It is to be understood that both the foregoing general description andthe following detailed description of the present invention areexemplary and explanatory and are intended to provide furtherexplanation of the invention as claimed.

BRIEF DESCRIPTION OF THE DRAWINGS

The accompanying drawings, which are included to provide a furtherunderstanding of the invention and are incorporated in and constitute apart of this application, illustrate embodiment(s) of the invention andtogether with the description serve to explain the principle of theinvention. In the drawings:

FIG. 1 is a view showing an example of a multi-channel network;

FIG. 2 is a schematic view showing a broadcasting system according to amobile vestigial sideband (MVSB);

FIG. 3 is a view showing an example of a service multiplexer shown inFIG. 2;

FIG. 4 is a view showing an example of a mobile service multiplexer;

FIG. 5 is a view showing an example of a transmitter shown in FIG. 2;

FIG. 6 is a view showing an example of a preprocessor shown in FIG. 5;

FIG. 7 is a view showing a cell information table (CIT) includingchannel information of each cell;

FIG. 8 is a view showing the syntax of an emergency alert table;

FIG. 9 is a view showing the syntax of including channel information foremergency alert broadcasting;

FIG. 10 is a view showing the syntax of a descriptor including channelinformation for emergency alert broadcasting;

FIG. 11 is a view showing the syntax of the emergency alert table;

FIG. 12 is a view showing an example of the syntax of the descriptorincluding the emergency alert broadcasting channel information;

FIG. 13 is a view showing the syntax of an emergency alert tableincluding the emergency alert broadcasting channel information;

FIG. 14 is a block diagram showing a broadcasting receiver according toan embodiment

FIG. 15 is a example of a demodulator of the broadcasting receiver inFIG. 14;

FIG. 16 is a block diagram showing a broadcasting receiver according toanother embodiment;

FIG. 17 is a block diagram showing a broadcasting receiver according toanother embodiment;

FIG. 18 is a block diagram showing a broadcasting receiver according toanother embodiment; and

FIG. 19 is a flowchart illustrating a method for receiving abroadcasting signal including an emergency alert message.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to the preferred embodiments of thepresent invention, examples of which are illustrated in the accompanyingdrawings. Wherever possible, the same reference numbers will be usedthroughout the drawings to refer to the same or like parts.

A broadcasting system for receiving a broadcasting signal while movingincludes a digital video broadcasting (DVB) system, a digital multimediabroadcasting (DMB) system, and a digital multimediabroadcasting-terrestrial handheld (DMB-TH) system. Hereinafter, forexample, a method for transmitting/receiving a broadcasting signalaccording to a modulation scheme called a mobile vestigial sideband(MVSB) scheme will be described.

In an advanced television system committee (ATSC) broadcasting system, abroadcasting signal receiver includes a service multiplexer and atransmitter.

Here, the service multiplexer may be located at a studio of eachbroadcasting station and the transmitter may be located at one or morespecific sites. A plurality of transmitters may share the samefrequency. In this case, the plurality of transmitters transmits thesame signal. The service multiplexer multiplexes main service data forfixed reception and mobile service data for mobile reception. Thetransmitter modulates the multiplexed broadcasting data and transmitsthe modulated broadcasting data. Hereinafter, for convenience ofdescription, a method for modulating the main service data for fixedreception and the mobile service data for mobile reception is called amobile VSB (MVSB). If the broadcasting data for mobile reception istransmitted, the transmitter modulates the mobile service data formobile reception such that the data can be stably received, regardlessof various distortions or noise which may occur in a transmissionchannel.

A broadcasting signal receiver can compensate for the signal distortionsand restore the broadcasting signal. Data communication between theservice multiplexer and the transmitter, both of which are separatedfrom each other, may be performed by various methods. For example, thestandard such as synchronous serial interface for transport of MPEG-2data (SMPTE-310M) may be used.

An MVSB transmission system can multiplex main service data and mobileservice data in the same channel and transmit/receive the multiplexeddata while being compatible with the existing ATSC VSB transmissionsystem. The MVSB system uses a multi-frequency network for broadcastingthe same program using different frequencies according to thetransmitters.

FIG. 1 is view showing an example of a multi-channel network. A mobileservice elementary stream (ES) is transmitted from a broadcastingstation 100 to an MVSB service multiplexer. In FIG. 1, mobile service ESis transmitted from the broadcasting station 100 to a first servicemultiplexer 110 and a second service multiplexer 120.

A broadcasting signal multiplexed by the first service multiplexer 110is transmitted through a first transmitter 130 and a broadcasting signalmultiplexed by the second service multiplexer 120 is transmitted througha second transmitter 140.

The transmitters can transmit the mobile service ES transmitted from theservice multiplexer 120 with different frequencies suitable for networkenvironments of the respective channels thereof. A range which isinfluenced by one network transmission system in a multi-channel networkis called as a cell.

In FIG. 1, a range which is influenced by a transmission system of thefirst transmitter 130 is a cell A and a range which is influenced by atransmission system of the second transmitter 140 is a cell B. Since auser should continuously view a broadcasting program even when the MVSBbroadcasting receiver moves between several cells, the broadcastingstation includes a cell ID corresponding to each transmitter in an MVSBbroadcasting signal and transmits the MVSB broadcasting signal.Accordingly, each transmitter may have a unique cell ID.

The broadcasting receiver can identify a cell, in which the broadcastingreceiver is currently located, using the cell ID included in the MVSBbroadcasting signal and continuously output the broadcasting contentseven when the broadcasting receiver moves between the cells. Inaddition, the broadcasting station can include channel information ofeach cell and the cell ID in the broadcasting signal and transmit thebroadcasting signal. Since the transmitters can transmit thebroadcasting signal transmitted from the same broadcasting stationthrough different physical channels, the channel information of eachcell may be changed.

If the receiver moves from the cell A to the cell B, the transmitter ofthe cell can be identified using the cell ID included in thebroadcasting signal. Then, the channel information of the identifiedtransmitter is analyzed. The receiver obtains the channel information ofthe cell B corresponding to the channel of the cell A which has beenviewed and changes the channel information of the cell A to the channelinformation of the cell B. The broadcasting signal is received accordingto the channel information of the cell B and is provided to the user.

FIG. 2 is a schematic block diagram showing the ATSC broadcasting systemin order to easily describe the present invention.

In the ATSC broadcasting system, a device for transmitting abroadcasting signal includes a service multiplexer and a transmitter.

Here, the service multiplexer may be located at a studio of eachbroadcasting station and the transmitter may be located at one or morespecific sites. A plurality of transmitters may share the samefrequency. In this case, the plurality of transmitters transmits thesame signal. The service multiplexer multiplexes main service data forfixed reception and mobile service data for mobile reception. Thetransmitter modulates the multiplexed broadcasting data and transmitsthe modulated broadcasting data. Hereinafter, for convenience ofdescription, a method for modulating the main service data for fixedreception and the mobile service data for mobile reception is called amobile VSB (MVSB). If the broadcasting data for mobile reception istransmitted, the transmitter modulates the mobile service data formobile reception such that the data can be stably received, regardlessof various distortions or noise which may occur in a transmissionchannel.

A broadcasting signal receiver can compensate for the signal distortionsand restore the broadcasting signal. Data communication between theservice multiplexer and the transmitter, both of which are separatedfrom each other, may be performed by various methods. For example, thestandard such as synchronous serial interface for transport of MPEG-2data (SMPTE-310M) may be used.

FIG. 3 is a view showing an example of the service multiplexer in thebroadcasting signal receiver in FIG. 2. The service multiplexer shown inFIG. 2 includes a main audio/video (A/V) system 210, mainancillary/control data system 220, a mobile A/V system 240, a mobileancillary/control data system 250, a main service multiplexer 230, amobile service multiplexer 260 and a transmission service multiplexer270.

Main service data is encoded and compressed by the main A/V system 210and is output to the main service multiplexer 230. If the number oftypes of main service data is greater than one, a plurality of main A/Vsystems may be included. The main service multiplexer 230 multiplexesthe output of the main A/V system 210 and various types of additionaldata 220 of the main service and outputs the multiplexed data to thetransmission service multiplexer 270.

Similarly, mobile service data is encoded and compressed by the mobileA/V system 240 and is output to the mobile service multiplexer 260. Ifthe number of types of mobile service data is greater than one, aplurality of mobile A/V systems may be included. The mobile servicemultiplexer 260 multiplexes the output of the mobile A/V system 240 andvarious types of additional data of the mobile service and outputs themultiplexed data to the transmission service multiplexer 270.

The transmission service multiplexer 270 multiplexes the output of themain service multiplexer 230 and the output of the mobile servicemultiplexer 260 and outputs the multiplexed data to the transmitter. Theoutput data of the transmission service multiplexer 270 may be expressedin the form of an MPEG-2 transport stream (TS) packet.

The transmission service multiplexer 270 can transmit the service datato the transmitter at a constant data rate. The transmission servicemultiplexer 270 can transmit the service data to the transmitter at aconstant data rate even when the service data transmitted to thetransmitter includes only the main service data or both the main servicedata and the mobile service data. For example, if the transmissionservice multiplexer 270 transmits the data to the transmitter at 19.39Mbps, the mobile service data is multiplexed with the main service dataand is transmitted within 19.39 Mbps. The mobile service data may besubjected to be error correction coding process in the transmitter andthus the data rate of the mobile service data may be reduced inconsideration of the error correction encoding process.

If the output of the service multiplexer needs to be maintained at theconstant data rate, for example, 19.39 Mbps, at least one of the mainservice multiplexer, the mobile service multiplexer and the transmissiondata multiplexer may insert null data or null packet in the multiplexeddata so as to match the data rate of the final output to the constantdata rate. Here, the null data may be generated in the multiplexer ormay be received from an external device.

FIG. 4 is a view showing an example of a mobile service multiplexer ofthe service multiplexer shown in FIG. 3. The mobile service multiplexershown in FIG. 4 includes a first multiplexer 311, a program tableinformation generator 312, a second multiplexer 313 and a packetconversion buffer 314.

The first multiplexer 311 multiplexes mobile data of an MPEG-2 TS formatand program table information, such as a program map table (PMT),generated by the program table information generator 312 and outputs themultiplexed data to the second multiplexer 313. The program tableinformation generator 312 generates information according to programspecific information (PSI) or program and system information protocol(PSIP). The PSI includes information such as the PMT, a programassociation table (PAT) and a network information table (NIT) and thePSIP includes a system time table (STT), a rating region table (RRT), amaster guide table (MGT), a virtual channel table (VCT), an eventinformation table (EIT) and an extended text table (ETT). Hereinafter,the information on the broadcasting signal which is transmitted in theform of at least one section, such as the PSI/PSIP, is called theprogram table information. The program table information generator 312can transmit physical channel information of the cells in addition to acell, which currently receives the signal, by the program tableinformation. Hereinafter, for convenience of description, it is assumedthat the physical channel information of the cells is included in theprogram table information called the NIT.

The second multiplexer 313 multiplexes the output of the firstmultiplexer 311 and the output of the program table informationgenerator 312 and outputs the multiplexed signal to the packetconversion buffer 314. The first multiplexer 311 includes a plurality ofmultiplexers for multiplexing plural pieces of mobile service data andthe PMT of the data. Here, one mobile service data may become a singleprogram. Information on a physical layer for real-time broadcasting,that is, information such as time slicing of a transmission signal and aburst length, may be included in the program table information. Thepacket conversion buffer 314 adjusts 188-byte transport stream outputfrom the second multiplexer 313 to a block length required in apreprocessor which will be described later.

FIG. 5 is a block diagram showing an example of the transmitter shown inFIG. 2.

The transmitter includes a demultiplexer 331, a packet jitter mitigater332, an M-VSB preprocessor 333, a first transmission data multiplexer334, a data randomizer 335, an RS encoder/non-systematic RS encoder 336,a data interleaver 337, a parity replacer 338, a non-systematic RSencoder 339, a trellis encoding module 340, a second transmission datamultiplexer 341, a pilot inserter 342, a VSB modulator 343, and an RFup-converter 344.

The demultiplexer 331 of the transmitter demultiplexes the data receivedfrom the transmission service multiplexer 270, divides the data into themain service data and the mobile service data, outputs the divided mainservice data to the packet jitter mitigater 332, and outputs the mobileservice data to the M-VSB preprocessor 333.

If the transmission service multiplexer 270 inserts the null data intothe data and then transmits the data in order to match the data rate tothe constant data rate, the demultiplexer 331 discards the null data byreferring to the identifier which is transmitted together, processesonly the remaining data, and outputs the processed data to acorresponding block. The demultiplexer 331 may set other information,such as control information necessary for transmission in the null data,and transmit the null data.

The M-VSB preprocessor 333 performs an additional encoding process withrespect to the mobile service data in order to rapidly cope with noiseand a channel variation. The mobile service data divided by thedemultiplexer 331 is output to the M-VSB preprocessor 333. The M-VSBpreprocessor 333 may randomize the mobile service data and perform anerror correction coding process. If the M-VSB preprocessor 33 performsthe randomizing process, the data randomizer 335 of the next stage mayomit the randomizing process of the mobile service data. The randomizerof the mobile service data may be equal to or different from arandomizer defined in the ATSC.

The main service data packet and the mobile service data packet based on188-byte units in data of a predetermined format output from the M-VSBpreprocessor 333 are multiplexed according to a predefined multiplexingmethod and are output to the data randomizer 335. The multiplexingmethod can be adjusted by various variables of the system design.

In the method for multiplexing the data by the first transmission datamultiplexer 334, as shown in FIG. 7, a burst period is provided on thetime axis, a plurality of data groups may be transmitted in the burstperiod and only the main service data may be transmitted in a non-burstperiod. In contrast, the main service data may be transmitted in theburst period. That is, as shown in FIG. 7, a plurality of successivemobile service packets forms one data group and the plurality of datagroups is mixed with the main service data packets so as to form oneburst. The mobile service data or the main service data may betransmitted in one burst period.

The main service data may exist in the burst period or the non-burstperiod. The numbers of main data packets in the main service data periodof the burst period and the main service data period of the non-burstperiod may be different from or equal to each other.

If the mobile service data is transmitted in the burst structure, thebroadcasting signal receiver for receiving only the mobile service datais turned on only in the burst period so as to receive the data and isturned off in the period in which only the main service data istransmitted, thereby reducing the power consumption of the receiver.

The packet jitter mitigater 332 readjusts a relative location of themain service data packet such that overflow or underflow does not occurin the buffer of the decoder in the broadcasting signal receiver. Sincethe mobile service data group is multiplexed with the main service datain the packet multiplexing process, the temporal location of the mainservice packet is relatively changed. The decoder (for example, the MPEGdecoder) of the device for processing the main service data of thebroadcasting signal receiver may receive and decode only the mainservice data, recognize the mobile service data packet as the nullpacket, and discard the mobile service data packet. Accordingly, whenthe decoder of the broadcasting signal receiver receives the mainservice data packet multiplexed with the mobile service data group,packet jitter may occur.

Since the decoder of the receiver includes multi-stage buffers for videodata and has a large size, the first transmission data multiplexer 334may generate the packet jitter. Due to the packet jitter, overflow orunderflow may occur in the buffer for the main service data of thebroadcasting signal receiver, for example, the buffer for audio data.

The packet jitter mitigater 332 knows the multiplexing information ofthe first transmission data multiplexer 334. If it is assumed that theaudio data packets are normally processed, the packet jitter mitigater332 may rearrange the audio data packets of the main service as follows.

First, if one audio data packet is included in the main service dataperiod of the burst period, for example, in the main service data periodinterposed between two mobile service data groups, the audio data packetis arranged at a foremost location of the main service data period, iftwo audio data packets are included in the main service data period ofthe burst period, the audio data packets are arranged at foremost andhindmost locations of the main service data period, and if at leastthree audio data packets are included in the main service data period ofthe burst period, two audio data packets are arranged at the foremostand hindmost locations of the main service data period and the remainingaudio data packet is arranged therebetween at a uniform interval.Second, the audio data packet is arranged at a hindmost location in themain service data period before the start of the burst period. Third,the audio data packet is arranged at a foremost location in the mainservice data period after the completion of the burst period. Thepackets other than the audio data are arranged in a period excluding thelocations of the audio data packets in input order.

If the locations of the main service data packets are relativelyreadjusted, a program clock reference (PCR) value is corrected. The PCRvalue is a time reference value for setting the time of the MPEGdecoder, which is inserted into a specific area of a TS packet and istransmitted. The packet jitter mitigater 332 may correct the PCR value.

The output of the packet jitter mitigater 332 is input to the firsttransmission data multiplexer 334. The first multiplexer 334 multiplexesthe main service data output from the packet jitter mitigater 332 andthe mobile service data output from the M-VSB preprocessor 333 to theburst structure according to the predefined multiplexing rule andoutputs the burst structure to the data randomizer 335.

The data randomizer 335 performs the same randomizing process as theexisting randomizer if the received data is the main service datapacket. That is, a sync byte in the main service data packet isdiscarded and the remaining 187 bytes are randomized using a pseudorandom byte generated therein and are output to the RSencoder/non-systematic RS encoder 336.

However, if the received data is the mobile service data packet, thedata randomizer 335 may discard the sync byte of 4-byte MPEG headerincluded in the mobile service data packet and randomize the remaining 3bytes. The remaining mobile service data excluding the MPEG header isoutput to the RS encoder/non-system RS encoder 336, without beingrandomized. In this case, the randomizing process is previouslyperformed by the M-VSB preprocessor 333. Known data (or a known datalocation holder) included in the mobile service data packet and aninitialization data location holder may be randomized or may not berandomized.

The RS encoder/non-systematic RS encoder 336 performs RS encodingprocess with respect to the data randomized by the data randomizer 335or bypassed data so as to add a 20-byte RS parity and then outputs theencoded data to the data interleaver 337. At this time, if the receiveddata is the main service data packet, the RS encoder/non-system RSencoder 336 performs a systematic RS encoding process so as to add the20-byte RS parity to the back of the 187-byte data, similar to an ATSCVSB system. If the received data is the mobile service data packet, the20-byte RS parity obtained by performing the non-systematic RS encodingprocess is inserted at the parity byte location decided in the packet.

The data interleaver 337 performs a convolutional interleaving processin the unit of bytes. The output of the data interleaver 337 is input tothe parity replacer 338 and the non-systematic RS encoder 339.

The memory of the trellis encoding module 340 may be first initializedsuch that output data of the trellis encoding module 340 located at thenext stage of the parity replacer 338 is set to known data defined bythe agreement between the transmitter and the receiver. The memory ofthe trellis encoding module 340 is first initialized before the receivedknown data sequence is trellis-encoded.

If a start part of the received known data sequence is theinitialization data location holder inserted by the M-VSB preprocessor333, initialization data is generated and is replaced with the trellismemory initialization data location holder immediately before thereceived known data sequence is trellis-encoded.

The value of the trellis memory initialization data is decided andgenerated according to the memory status of the trellis encoding module340. Due to the influence of the replaced initialization data, the RSparity may be calculated again and may be replaced with the RS parityoutput from the data interleaver 337.

The non-systematic RS encoder 339 receives the mobile service datapacket including the initialization data location holder, which will bereplaced with the initialization data, from the data interleaver 337 andreceives the initialization data from the trellis encoding module 340.The initialization data location holder of the received mobile servicedata packet is replaced with the initialization data, the RS parity dataadded to the mobile service data packet is removed, and a newnon-systematic RS parity is calculated and is output to the parityreplacer 338. Then, the parity replacer 338 selects the output of thedata interleaver 337 with respect to the data in the mobile service datapacket, selects the output of the non-systematic RS encoder 339 withrespect to the RS parity, and outputs the selected data to the trellisencoding unit 340.

If the main service data packet is received or if the mobile servicedata packet no including the initialization data location holder to bereplaced is received, the parity replacer 338 selects and outputs the RSparity and the data output from the data interleaver 337 to the trellisencoding module 340 without alteration.

The trellis encoding module 340 converts the data based on byte unitsinto the data based on symbol units, performs 12-way interleaving,performs the trellis encoding process, and outputs the encoded data tothe second transmission data multiplexer 341.

The second transmission data multiplexer 341 inserts a field sync signaland a segment sync signal to the output of the trellis encoding module340 and outputs the inserted data to the pilot inserter 342. The datainto which the pilot is inserted by the pilot inserter 342 isVSB-modulated by the VSB modulator 343 and is transmitted to thebroadcasting signal receiver through the RF up-converter 343.

The transmitter transmits various transmission parameters of thetransmission signal such as the main service data or the mobile servicedata and the broadcasting signal receiver needs to receive thetransmission parameters of the transmitted signal in order to normallyreceive the transmitted signal. For example, in order to transmit themobile service data, information indicating how the signals of thesymbol area are encoded is required and information indicating how themain service data and the mobile service data are multiplexed isrequired. A cell identifier may be required in the multi-frequencynetwork environment. Here, information on the transmission parameter iscalled signaling information. In the embodiment shown in FIG. 5, thesignaling information may be inserted by the preprocessor 333 or thesecond transmission data multiplexer 341 so as to be transmitted. If thesecond transmission data multiplexer 341 inserts the signalinginformation, the signaling information may be inserted into a field syncsegment area.

FIG. 6 is a view showing an example of the pre-preprocessor shown inFIG. 5. The pre-preprocessor shown in FIG. 6 may include an M-VSB datarandomizer 401, a RS frame encoder 402, an M-VSB block processor 403, agroup formatter 404, a data deinterleaver 405 and a packet formatter406.

The M-VSB randomizer 401 randomizes the received mobile service data andoutputs the randomized data to the RS frame encoder 402, for errorcorrection encoding. If the M-VSB randomizer 401 randomizes the mobileservice data, the data randomizer 335 located at the next stage in FIG.5 may omit the randomizing process of the mobile service data.

The RS frame encoder 402 performs the error correction encoding processwith respect to the randomized mobile service data. If the RS frameencoder 402 performs the error correction encoding process, burst errorwhich may occur by a variation in propagation environment is distributedwhile making the mobile service data robust so as to cope with thepropagation environment which rapidly varies. The RS frame encoder 402may include a process of mixing mobile service data having apredetermined size in the unit of data rows.

Hereinafter, as one embodiment, the error correction encoding processmay be performed by performing the RS encoding method or the cyclicredundancy check (CRC) encoding method. If the RS encoding method isperformed, parity data which will be used for error correction isgenerated and, if the CRC encoding method is performed, CRC data whichwill be used for error detection is generated.

The RS encoding method may use a forward error correction (FEC)structure. The CRC data generated by the CRC encoding process mayindicate whether the mobile service data is damaged by the error whilebeing transmitted through the channel. The error correction encodingprocess may use other error detection encoding methods other than theCRC encoding method. Alternatively, the overall error correctioncapability of the receiver can be increased using the error correctionencoding method. The mobile service data encoded by the RS frame encoder402 is input to the M-VSB block processor 403.

The M-VSB block processor 403 encodes the received mobile service dataat G/H encoding rate again and outputs the encoded data to the groupformatter 404. The M-VSB block processor 403 separates the receivedmobile service data based on the byte units into data based on bitunits, encodes the separated G-bit data to H-bit data, converts the datainto data based on byte units, and outputs the data based on byte units.For example, if 1-bit input data is encoded to 2-bit data and the 2-bitdata is output, G becomes 1 and H becomes 2. If 1-bit input data isencoded to 4-bit data and the 4-bit data is output, G becomes 1 and Hbecomes 4. In the present invention, for convenience of description, theformer case is called encoding of 1/2 encoding rate (also called 1/2encoding) and the latter case is called encoding of 1/4 encoding rate(also called 1/4 encoding). The 1/4 encoding has higher error correctioncapability than the 1/2 encoding. Accordingly, the group formatter 404may allocate the data encoded at the 1/4 encoding rate to an area havinglow reception capability and allocate the data encoded at the 1/2encoding rate to an area having high reception capability, therebyreducing a difference in reception capability.

The M-VSB block processor 403 may receive the signaling informationincluded in the transmission parameter information. The data containingthe signaling information may be subjected to the 1/2 encoding or the1/4 encoding. The signaling information is the information necessary forreceiving and processing the data included in the data group by thebroadcasting signal receiver and may include cell identifierinformation, data group information, multiplexing information and burstinformation.

The group formatter 404 inserts the mobile service data output from theM-VSB block processor 403 into a corresponding area in the data groupformed according to a predetermined rule. In conjunction with the datadeinterleaving, various types of location holders or known data may beinserted into the corresponding area in the data group. The data groupmay be separated into at least one layered area and the type of themobile service data inserted into each area may vary according to thecharacteristics of the layered area. For example, each layered area maybe classified according to the reception capability within the datagroup.

The group formatter 404 may insert the signaling information such as thetransmission parameter information into the data group independent ofthe mobile service data. When the generated known data is inserted intothe corresponding area of the mobile service data group, the groupformatter 404 may insert the signaling information into at least aportion of the area into which the known data can be inserted, insteadof the known data. For example, if a long known data sequence isinserted into the start part of a body area of the mobile service datagroup, the signaling information is inserted into a portion of the startpart, instead of the known data. In this case, a portion of the knowndata sequence inserted into the remaining area excluding the area, intowhich the signaling information is inserted, may be used for capturingthe start point of the mobile service data group and the other portionmay be used for channel equalization in a reception system.

The group formatter 404 may insert an MPEG header location holder, anon-systematic RS parity location holder and a main service datalocation holder in conjunction with the data deinterleaving of the nextstage, in addition to the encoded mobile service data output from theM-VSB block processor 403.

The reason why the main service data location holder is inserted isbecause an area in which the mobile service data and the main servicedata are mixed exists on the basis of the data after the datainterleaving. For example, the location holder for the MPEG header isallocated to the foremost location of each packet on the basis of theoutput data after the data deinterleaving.

The group formatter 404 may insert the known data generated by apredetermined method or insert the known data location holder forinserting the known data later. The location holder for initializationof the trellis encoding module may be inserted into a previous area ofthe known data sequence. The size of the mobile service data which canbe inserted into one data group may vary according to initialization ofthe trellis inserted into the data group or the size of the known data,the MPEG header and the RS parity.

The data deinterleaver 405 deinterleaves the data and the locationholder in the data group output from the group formatter 404 as theinverse process of the interleaving and outputs the deinterleaved datato the packet formatter 406.

The packet formatter 406 may remove the main service data locationholder and the RS parity location holder allocated for thedeinterleaving, add 1-byte MPEG sync signal to a 3-byte MPEG headerlocation holder with respect to the remaining data portions, and inserta 4-byte MPEG header.

If the group formatter 404 inserts the known data location holder, thepacket formatter 406 may include actual known data to the known datalocation holder and output the known data location holder withoutadjustment. Then, the packet formatter 406 divides the data in thepacket-formatted data group into mobile service data packets (that is,the MPEG TS packets) based on 188-byte units and outputs the divideddata to the multiplexer. The packet formatter 406 may insert thesignaling information into at least a portion of the known data areainstead of the known data and output the inserted data. If the knowndata location holder is inserted into the start part of the body area ofthe mobile service data group, the signaling information may be insertedinto a portion of the known data location holder.

If the signaling information is inserted, the inserted signalinginformation may be block-encoded for a short period and may be insertedor a predefined pattern may be inserted according to the signalinginformation. The body areas of the mobile service data group may havedifferent known data patterns. Accordingly, in the reception system,only symbols in a promised period may be divided from the known datasequence and be recognized as the signaling information.

FIGS. 7 to 10 show the example of transmitting the broadcasting signalof which mobile reception is possible. Hereinafter, a method fortransmitting/receiving a broadcasting signal when a broadcasting signalreceiver changes a cell and receives the broadcasting signal will bedescribed.

The method for transmitting/receiving the broadcasting signal accordingto the present embodiment can include a cell identifier in signalinginformation and transmit/receive the signaling information. Informationon a cell for receiving a current broadcasting signal and the othercells, for example, information on a current cell and adjacent cells,may be set in program table information and may be transmitted/received.

The broadcasting signal receiver may determine whether the cell forreceiving the broadcasting signal is changed, from the power of thereception signal. If the cell is changed, the broadcasting signalreceiver may obtain channel information from the changed cell using theprogram table information and output the program of the same channelbefore and after the cell is changed.

The method for transmitting/receiving the broadcasting signal accordingto the present embodiment can transmit/receive the identifier of thecell using the program table information called the PSI/PSIP or cantransmit/receive the identifier of the cell using the signalinginformation including the transmission parameter information.

If the receiver moves between the cells and the cell information ischanged, the PSI or PSIP information may be changed and the receiver canobtain the changed cell information according to the changed programtable information. For example, if the PSI or the PSIP information ischanged, the broadcasting signal receiver can know that the programtable information is updated, through the MGT. The MGT defines thepacket identifier (PID) of the PSIP table excluding the STT, a versionnumber and a table size. Accordingly, if the table information in theMGT is changed, the version number of the MGT is changed and thus thechanged table can be received again. If the CIT which is the programtable information having the cell information is changed, thebroadcasting signal receiver can recognize the movement between thecells through the MGT.

FIG. 7 is a view showing table type values defined in the MGT which isthe program table information having cell information. The MGT deliversthe PID value of the version value of every table excluding the STT.That is, the broadcasting signal receiver checks the version-up of otherprogram table information through the MGT and does not check the versionof the table information, thereby reducing the load of the broadcastingsystem. In the present embodiment, the type of the CIT for deliveringthe cell information is defined in the MGT so as to check whether theversion of the CIT is updated. FIG. 7 shows an example in which thetable_type of the CIT is defined by 0x0022. The broadcasting signalreceiver can change the channel using the physical channel informationof the changed cell using the CIT information and thus the viewer cancontinuously view the broadcasting program of the channel which has beenviewed.

FIG. 8 is a view showing a cell information table (CIT) includingchannel information of each cell.

The CIT may be transmitted as one piece of section information such asthe PSIP and include the channel information of each cell. The versionof the CIT may be managed by a master guide table (MGT) similar to theother tables defined in the ATSC A/65.

The MGT defines the PID, the version number and the table size of a PSIPtable excluding a system time table (STT). For example, if theinformation on the PSI or the PSIP is changed, the broadcasting receivercan recognize that the program table information is updated, through theMGT.

Accordingly, if the table information of the MGT is changed, the versionnumber of the MGT is changed and the broadcasting receiver can receivethe changed table again. If the broadcasting receiver moves between thecells so as to change the CIT which is the program table informationhaving the cell information, the movement of the broadcasting receiverbetween the cells can be recognized through the MGT. The broadcastingreceiver can change the channel to the channel information of thechanged cell using the CIT information, and the user can continuouslyview the broadcasting program of the channel which has been viewed.

Next, the syntax of the CIT shown in FIG. 8 will be described.

A “table_ID” field is the syntax for identifying the CIT and may be, forexample, set to 0xCE. A “section_syntax_indicator” field may be set to 1and indicates that the section follows the general section syntax. A“private_indicator” field may be set to 1. A “section_length” field is a12-bit field which indicates the length of the section.

A “transport_stream_id” field is a 16-bit field which includesinformation for identifying the transport stream. A “version_number”field is a 5-bit field which includes the version information of theCIT. A “current_next_indicator” field is a 1-bit field which may be setto 1. This indicates that the sent table is always applied.

A “section_number” field is an 8-bit field which includes theinformation on the section number. A “last_section_number” field is an8-bit field which includes the information on the last section number. A“protocol_version” field is an 8-bit field which includes the versioninformation of the protocol of the table.

A “num_cells_in_section” field is an 8-bit field which includes theinformation on the number of cells defined in the CIT. The number ofcells may be equal to the total number of transmitters to which thebroadcasting station transmits the broadcasting signal. The informationon all the transmitters to which the broadcasting station transmits thebroadcasting signal may be defined in the CIT.

A “cell_id” field is an 8-bit field which includes the cell ID of thetransmitter to which the broadcasting station transmits the broadcastingsignal. The cell IDs may one-to-one correspond to the transmitters towhich the broadcasting station transmits the broadcasting signal. A“cell_text” field is a 7×16-bit field which includes the nameinformation of the transmitter. A “cell_location” field is a 7×16-bitfield which includes the information on an area in which the transmitteris located.

A “num_channels_in_cell” field is an 8-bit field which includes theinformation on the number of channels of the broadcasting stationtransmitted from the transmitter. For example, in the broadcastingsignal transmitted from the broadcasting station including two channels,the “num_channels_in_cell” field is set to 2.

A “major_channel_number” field is a 10-bit field which includes theinformation on the major channel number of the channel transmitted fromthe transmitter. A “minor_channel_number” field is a 10-bit field whichincludes the information on the minor channel number of the channeltransmitted from the transmitter. A “modulation_mode” field is an 8-bitfield which includes the information on the modulation mode of thechannel.

A “carrier_frequency” field is a 32-bit field which includes theinformation on the carrier frequency for transmitting the broadcastingsignal of the channel. A “channel_TSID” field is a 16-bit field whichincludes the information for identifying the transport stream of thechannel. A “program_number” field is a 16-bit field which includes theinformation on the program number of the channel.

A “descriptor_length” field is a 10-bit field which includes theinformation on the length of the following descriptor. The descriptorincludes three levels such as a descriptor of a channel level, adescriptor of a cell level and a descriptor of a CIT level. A “CRC_32”field is a 32-bit field which includes the code information forcorrecting an error.

The receiver may obtain the identifier of the changed cell, obtain thesignaling information or the EAT from the MGT or the received signal,obtain the channel information of the changed cell from the CIT, andcontinuously output the broadcasting signal, even when the receivermoves between the cells. When the receiver receives the emergency alertmessage, the contents of the received emergency alert information may bedisplayed on a screen or the channel which is currently being viewed maybe changed to an emergency alert channel. In the case where the receivedemergency alert message is displayed on the screen which currentlydisplays a broadcasting program, the channel is not changed and thus aproblem does not occur.

However, in the case where the channel which is currently being viewedmay be changed to the emergency alert channel, the broadcasting programof the emergency alert channel should not be stopped even when thereceiver moves between the cells, in order to continuously output theemergency alert. If the emergency alert status is released even when thereceiver moves between the cells, the channel is returned to theoriginal channel which has been viewed.

In order to solve such requirements, the broadcasting station mayinclude the emergency alert channel information of each cell in the CITincluding the channel information of each cell and transmit the CIT tothe receiver. The cell ID, the emergency alert message contents and theemergency alert channel information are included in the emergency alerttable, which is then transmitted to the receiver.

The cell ID and the emergency alert channel information may be definedin the fields of the emergency alert table so as to be transmitted ormay be defined in a separate descriptor and included in the emergencyinformation table so as to be transmitted. FIGS. 11 and 12 show examplesof transmitting/receiving the emergency information table using the cellID and the emergency alert channel information.

FIG. 9 is a view showing an example of the MGT for describing a methodfor transmitting/receiving a broadcasting signal according to anembodiment. Hereinafter, the method for transmitting/receiving thebroadcasting signal according to an embodiment will be described withreference to FIG. 9.

In the method for transmitting/receiving the broadcasting signal, if thehandover occurs, the broadcasting signal receiver checks the versionnumber of the MGT so as to recognize the change of the cell. FIG. 9shows an example of defining the cell identifier defined in the CIT inthe reserved field of the MGT. In addition to the field shown in FIG. 9,the cell identifier defined in the CIT may be configured by variousmethods.

In FIG. 9, the “cell_id” field is located next to the“table_id_extension” field of the MGT and includes the index of the cellincluded in the CIT. The MGT configures a “table_type” field withrespect to a “table_defined” field. The broadcasting signal receiver cancheck whether the program table information described in FIG. 7 isupdated or changed according to the “table_type” field. A“table_type_PID” field configures the PID of the packet for deliveringthe “table_type” field.

The broadcasting signal receiver can obtain the channel informationaccording to the “cell_id” field defined in the MGT through the CITinformation shown in FIG. 12 in the program table information.

The broadcasting signal receiver may parse the MGT which is one of theprogram table information, obtain the current cell ID, find the cell IDof the CIT having the same cell ID as the cell ID of the MGT, and obtainthe channel information of the changed cell. If the broadcasting signalreceiver moves to another cell, the MGT is received again and thetransport stream information of the CIT using the cell ID of the MGT asthe index is updated. Accordingly, the channel information such as“major_channel_number”, “minor_channel_number”, “modulation mode” (forexample, QAM, VSB, etc.), “carrier_frequency”, and “program number”field configured in the CIT can be obtained.

FIG. 10 is a view showing an example of a descriptor for describing amethod for transmitting/receiving a broadcasting signal according toanother embodiment. Hereinafter, the method for transmitting/receivingthe broadcasting signal according to another embodiment will bedescribed with reference to FIG. 10.

In FIG. 10, the “cell_id” field may be delivered through the descriptorincluded in the MGT. In FIG. 10, the descriptor for parsing the“cell_id” field from the MGT is called a “cell_link_descriptor” field.The descriptor shown in FIG. 10 may be parsed from the descriptor of theMGT shown in FIG. 9. The descriptor for parsing the “cell_id” fieldshown in FIG. 10 may include a “descriptor_tag” field of 0xAB, a“descriptor_length” in byte units, a “cell_id” field, and a “reserved”field.

If the “cell_id” field is parsed from the descriptor of the MGT which isupdated at the time of occurrence of handover, the broadcasting signalreceiver can obtain the channel information of the changed cell usingthe same “cell_id” field included in the CIT.

FIG. 11 is a view showing the syntax of the emergency alert table. Now,the syntax configuring the EAT shown in FIG. 11 will be described.

A “table_ID” field is the syntax for displaying the emergency alertmessage table and may be, for example, set to 0xD8. A“section_syntax_indicator” field may be set to 1 and indicates that thesection follows the general section syntax. A “section_length” fielddefines the number of bytes which remain in the section and may be setto be less than 4093.

A “table_id_extension” field includes the extension information of the“table_id” field and may be set to 0x0000. A “sequence_number” fieldindicates the sequence of the emergency alert message and may beincreased from 0 to 31 if the semantic of the message is changed. Thisfield may indicate the version of the emergency alert message.

A “current_next_indicator” field is a 1-bit field which may be set to 1.This field indicates that the sent table is always applied. A“section_number” field is an 8-bit field which includes the informationon the section number and may be set to 0x00dmfh. A“last_section_number” field is an 8-bit field which includes theinformation on the last section number. A “protocol_version” field is an8-bit field which includes the version information of the PSIP protocolwhich is the protocol of the above-described table.

An “EAS_originator_code” field indicates the entity for generating theemergency alert system (EAS). An “EAS_event_code_length” field indicatesthe length of the “EAS_event_code”. An “EAS_event_code” field includesthe information indicating the type of the EAS, for example, the type ofthe emergency such as an earthquake, a flood or a terrorist threat orthe emergency information such as a strong earthquake, a mediumearthquake and a weak earthquake.

A “nature_of activation_text_length” field indicates the length of“nature_of_activation_text”. For example, if the value of the value ofthe “nature_of_activation_text_length” field is “0”, it is indicatedthat the “nature_of_activation_text” field is not included in theemergency alert message.

A “nature_of_activation_text” field may include a specific syntaxindicating the textual representation of the event code displayed on thescreen. For example, when an earthquake occurs, a message “occurrence ofearthquake” which will be displayed on the screen may be included.

An “alert_message_time_remaining” field indicates the residual outputtime of the emergency alert message. For example, the residual outputtime may be set in the unit of 0 to 120 seconds and, if the field valueis 0, the output time may indicate an infinite duration. Alternatively,the “alert_message_time_remaining” field may indicate the duration timeduring when the emergency alert message which is an interrupt service isdisplayed until original broadcast service returns, in second units.That is, this field indicates the time during when the message isoutput.

An “event_start_time” field may indicate the start time of the EAM eventafter 00 hours UTC, Jan. 6, 1980 in second units.

The start time of the EAM event is compared with the STT time of thechannel on the basis of the GPS time, and the broadcasting receiverignores the EAT if the start time of the EAM event is earlier than theSTT time of the channel. In contrast, if the start time of the EAM eventis later than the STT time of the channel, the start time of the EAMevent is compared with the value of the “event_duration” field so as todetermine whether the start time of the EAM event will be loaded to thememory of the broadcasting receiver. The “event_duration” fieldindicates the duration of the emergency alert event in minute units. Azero value may indicate that it is not determined how long the EAM eventis maintained.

The broadcasting receiver may delete a past emergency alert event, whichis stored in the memory of the broadcasting receiver but is no longernecessary, using the “event-start-time” field and the “event_duration”field. An “alert_priority” field may indicate the syntax for displayingthe priority or the importance of the emergency.

Table 1 shows the example of the meaning corresponding to the value ofthe “alert_priority” field according to the present invention.

TABLE 1 Alert Channel Priority Meaning Tuning 0 Test Message X 1-7Reserved X 8 Medium Priority: Message Scrolling X  9-14 Reserved X 15 High Priority: Message Scrolling and ∘ Channel Tuning

As shown in Table 1, for example, if the priority is “0”, thebroadcasting transmitter may transmit only a test message and, if thepriority is “8”, information for controlling the message related to theemergency to be scrolled on the screen of the broadcasting receiver maybe transmitted.

If the priority is “15”, that is, if the priority is highest, theinformation for controlling the message related to the emergency to bescrolled on the screen of the broadcasting receiver may be transmittedand information for forcedly tuning the channel to a specific channelfor reporting the news related to the emergency may be transmitted. Thespecific channel may be, for example, the existing broadcasting channelor may be set to a broadcasting channel with a new frequency in a newcell. The above-described values are only exemplary.

A “details_channel_source” field clearly defines whether thebroadcasting channel of the emergency alert message is an analog channelor a digital channel. For example, the channel type of the emergencybroadcasting program according to the value of the“details_channel_source” field may be defined as shown in Table 2.

TABLE 2 Value Meaning 0x00 (00) [Reserved for future use] 0x01 (01)Analog channel 0x02 (10) Digital channel 0x03 (11) [Reserved for futureuse]

For example, if the value of the “details_channel_source” field is “00”or “11”, “reserved for future use” may be defined, if the value of the“details_channel_source” field is “01”, the analog channel may bedefined, and, if the value of the “details_channel_source” field is“10”, the digital channel may be defined. In this case, even when theminor channel number is 0, it is easily determined whether the emergencychannel is the analog channel or the digital channel by Table 2.

An “alert_text_length” field includes the information on the total bytenumber of the “alert_text( )” field. For example, if the value of the“alert_text_length” field is 0, it is indicated that the “alert_text( )”field is not included in the emergency alert message.

An “alert_text_rate” field indicates the scroll rate of scroll dataparsed in the “alert_text( )” field, that, the emergency alert contents.At this time, the scroll rate may be decided to an adequate rate forallowing a viewer to easily recognize the scroll data by referring tothe scroll data size (that is, the value of the “alert_text_length”field) and the emergency alert message duration (that is, the value ofthe “alert_message_time_remaining” field).

Alternatively, the “alert_text_rate” field may include information fordifferently setting the scroll rate of the text containing the emergencyalert message according to the value of the field (“alert_priority”) forindicating the importance of the emergency. For example, 16 bits areallocated to the “alert_text_rate” field and the scroll rate may berepresented by an unsigned integer number (uimsbf). At this time, a timeperiod from a time point when a first character starts to be scrolled toa time point which the character disappears from the screen may bedescribed as the scroll rate in second units. Alternatively, time periodfrom a time point when a first character of the emergency contentsstarts to be scrolled to a time point when the scrolling of a lastcharacter thereof is finished may be described in second units. An“alert_text( )” field may become a data field including a specificsyntax (for example, “multiple_string_structure( )” or the like) forrepresenting the textual description of the emergency alert on theon-screen-display (OSD). The emergency alert text may be set to beslowly scrolled from bottom to top or the right to the left of thescreen of the broadcasting receiver.

A “location_code_count” field counts the region definition which follows“for loop” and the value thereof may be an integer number from 1 to 31.

A “country_code” field is an 8-bit field which indicates the countrycode related to the emergency. Since the “country_code field having 8bits can theoretically represent 256 countries, it is possible tosufficiently specify about 210 to 220 countries which exist currently.The number, 8, of bits allocated to the “country_code” field is onlyexemplary and the number of bits may be less than or greater than 8.That is, the number of bits allocated to the “country_code” field may beselected by a designer.

A “state_code” field represents a state or a territory related to theemergency and may have a value of 0 to 99. The “state_code” field may becoded according to the FIPS number codes of the state and the territoryand, if the value of the field is 0, it is indicated that every state isin the emergency.

A “state_subdivision_code” field defines state division. A “county_code”field represents a specific county of the state related to theemergency. The “county_code” field may be coded according to the FIPSnumber codes of the state and the territory and, if the value of thefield is 0, it is indicated that every county is in the emergency.

Although the regional name of the administrative division of the UnitedStates is used in the regional definition, the regional name is notintended to restrict the scope of the present invention and is onlyexemplary.

An “exception_count” field counts an exception service which follows‘for loop’. If an “exception_major_channel_number” field is not 0, themajor channel number of the exception service associated with in-bandservice information (SI) may be expressed. If an“exception_minor_channel_number” field is not 0, the minor channelnumber of the exception service associated with the in-band SI may berepresented. A “descriptors length” field includes the information onthe length of the following descriptor. A “CRC_32” field is a 32-bitfield which includes the code information for correcting an error.

FIG. 12 is a view showing an example of the syntax of the descriptorincluding the emergency alert broadcasting channel information. Thedescriptor may be included in an EAT table shown in FIG. 11 so as to betransmitted.

A “descriptor_tag” field includes the identifier for identifying thedescriptor. The value of the field may be, for example, set to 0xEA. A“descriptor_length” field may include the information on the length ofthe descriptor.

A “cell_ID” field may include the cell ID of the current cell whichtransmits the emergency alert broadcasting signal. A“details_major_channel_number” field may include information on themajor channel number of the emergency alert broadcasting channel. A“details_minor_channel_number” field may include information on theminor channel number of the emergency alert broadcasting channel.

A “carrier_frequency” field is a 32-bit field which may includeinformation on the carrier frequency for transmitting the broadcastingsignal of the emergency alert broadcasting channel.

A “details_channel_program_Number” field may include information on theprogram number of the emergency alert broadcasting channel.

A “details_channel_tsID” field is a 16-bit field which may includeinformation for identifying the transport stream of the emergency alertbroadcasting channel.

FIG. 13 is a view showing the syntax of an emergency alert tableincluding the emergency alert broadcasting channel information.

In the emergency alert table shown in FIG. 13, the information includedin the emergency alert descriptor shown in FIG. 11 is defined in fieldsof the table. The description of the fields of the emergency alert tableshown in FIG. 13 is equal to that of the fields of FIG. 11.

A packet identifier (PID) of the EAT may be set such that the PID andthe version number are managed by the MGT or may have a fixed PID whichis not managed by the MGT. In the former case, the broadcasting receivercannot immediately check the EAT in numerous tables of the PSIP data andcan obtain the EAT by checking the PID defined in the MGT. In the lattercase, the EAT can be identified by the PID of the EAT and the cell IDcan be obtained from the identified EAT.

If the emergency alert tables shown in FIGS. 11 to 13 are used, it ispossible to continuously view the emergency alert message or theemergency alert channel although the broadcasting receiver moves betweenthe cells. Although the receiver moves between the cells, if theemergency alert status is cancelled, the channel can be returned to theoriginal channel which has been viewed.

For example, it is assumed that the broadcasting receiver receives thebroadcasting signal from the cell A. If the emergency alert tables shownin FIGS. 11 to 13 are received while the broadcasting signal is receivedfrom the cell A, the broadcasting receiver outputs the emergency alertmessage included in the emergency alert table on the screen or tunes thechannel to the emergency alert channel.

If the broadcasting receiver moves from the cell A to the cell B whilethe emergency alert message is output on the screen, the cell ID isobtained. The cell ID can be obtained from the signaling information ofthe received signal, the MGT, or the EAT, as described above. The cell Bis identified by the obtained cell ID and the channel information foroutputting the emergency alert message is obtained from the channelinformation of the cell B included in the CIT. The emergency alert tablecan be received from the cell B and the emergency alert message can beoutput on the screen.

At this time, if the emergency is cancelled, the broadcasting receivercan tune the channel to the original channel which has been viewed oroutput the original program which has been viewed. When the emergencyalert is finished, the broadcasting receiver can check through whichchannel of the cell B the channel or the program, which has beenreceived from the cell A, is received, using the cell ID of the current(cell B) and the channel information of the CIT. Accordingly, even whenthe emergency alert is finished after the cell is changed, the channelwhich has been received from the cell A can be received from the cell B.

FIG. 14 is a view showing a broadcasting signal receiver according to anembodiment. The broadcasting signal receiver shown in FIG. 17 includes atuner 510, a demodulator 520, a demultiplexer 530, a decoder 540, anoutput unit 550, a controller 560, a memory 570, and a program tableinformation decoder 580.

The operation of the broadcasting signal receiver according to thepresent embodiment will be described with reference to FIG. 14.

The tuner 510 receives the broadcasting signal including the cellinformation and selects and outputs the broadcasting signal of a channelaccording to a control signal of the controller 560 among thebroadcasting signals received from the current cell.

The demodulator 520 may demodulate and output the received signal. Thesignaling information including the cell information may be output andtransmitted to the controller 560. The demodulator 520 will be describedin detail with reference to FIG. 15.

The demultiplexer 530 may demultiplex program table information(PSI/PSIP) and an audio/video stream in the received signal.Alternatively, a broadcasting stream which will be recorded in orreproduced from a digital recording device may be received. For example,an input signal according to the IEEE1394 may be directly receivedwithout the tuner.

The decoder 540 may decode the audio/video broadcasting signaldemultiplexed by the demultiplexer 530. The decoder 540 decodes theaudio/video elementary stream packet and outputs the decoded audio/videosignal to the output unit 550.

The output unit 550 receives and outputs the audio/video signal decodedby the decoder 540. The output unit 550 includes an on-screen-display(OSD) unit for outputting a graphic signal displayed on a displayscreen.

The program table information decoder 580 may decode the program tableinformation demultiplexed by the demultiplexer 530 and temporarily storethe decoded table information. The program table information decoder mayparse the table including the cell information, that is, the MGT,extract the cell information, and output the obtained cell informationto the controller 540.

The controller 560 includes an interface for receiving the controlsignal from the user. The controller 560 stores channel map informationin which a physical channel and a virtual channel are mapped such thatthe tuner 510 selects the channel, and controls the decoder 540 suchthat the broadcasting stream is output according to the channel requestof the user. If the program table information decoder 580 parses theupdated table information, the controller 560 stores the updated channelinformation in the channel map. The controller 560 may store othercontrol information including information necessary for the handover ofthe broadcasting signal receiver, information on an application and therequest information of the user in the memory 570.

When the program table information decoder 580 extracts the cellinformation, the controller 560 may obtain the channel information ofthe changed cell using the CIT information decoded by the program tableinformation decoder 580. The controller 560 controls the tuner 510 totune the channel information of the changed cell such that thebroadcasting contents received from the previous cell are output. Thecontroller 560 may control the demodulator 520, the demultiplexer 530and the decoder 540 to process the tuned signal.

The CIT and EAT table demultiplexed by the demultiplexer 50 is output tothe program table information decoder 580. The program table informationdecoder 580 collects, sections having the same table ID (table_id),parses the table, and stores the parsed result in the program tableinformation storage unit.

Meanwhile, the controller 560 may operate an application manager,execute a native application program stored in the memory 570 andperform a general function such as channel switching. The nativeapplication program indicates software which is installed at the time ofshipment of the reception system. If the reception system receives theuser's request through a user interface (UI), the controller 560displays information corresponding to the user's request on the screenthrough a graphic user interface (GUI).

The application manager controls a channel manager so as to perform achannel-related operation, that is, the management of a channel map, andcontrols the program table information decoder 580.

If the EAT information is received, the application manager controls atext related to the emergency to be output on the screen according tothe parsed EAT information. The application manager determines whetherthe received EAT information is equal to the EAT information which ismost recently received and does not process the received EAT informationif it is determined that the received EAT information is equal to theEAT information which is most recently received.

While the text related to the emergency is output on the display unit(not shown), the size, contrast, or color of the text may be adjustedusing the value of an “alert_priority” field included in the EAT.

For example, if the value of the “alert_priority” field is 8, a texthaving a relatively small size can be output and, if the value of the“alert_priority” field is 15, a text having a relatively large size canbe output since an important emergency occurs.

Alternatively, if the value of the “alert_priority” field is 8, a texthaving relatively low contrast can be output and, if the value of the“alert_priority” field is 15, a text having relatively high contrast canbe output since an important emergency occurs. The application managercontrols the channel manager and the tuner such that the channel isforcedly tuned to the emergency alert channel according to the“alert_priority” field.

As described above, the emergency channel may be the existingbroadcasting channel or a special frequency channel which is operatedonly in an emergency.

The application manager may store the cell ID of the cell from which thebroadcasting signal has been received and the channel information of thechannel which has been viewed, before tuning the channel to theemergency alert channel. If the emergency is cancelled, the applicationmanager may return the channel to the channel which has been viewed,using the channel information of the channel and the cell ID, both ofwhich are stored in the memory 570.

If it is determined that the cell ID of the cell in which thebroadcasting receiver is located and the stored cell ID are differentfrom each other at the time of cancellation of the emergency, theapplication manager analyzes the CIT and the channel information of thechannel map storage unit and returns the channel to the original channelin which the original program the user has viewed has been transmitted,using the channel information of the cell.

The controller 560 may operate the system manager. The system managermay control booting of the reception system by turning on/off the powersource and store a downloaded software image in the memory 570. Thememory 570 stores an operating program such as an operating systemnecessary for operating the reception system and an application programfor performing a data service function.

The operating program and the application program stored in the memory570 may be updated or corrected to a newly downloaded program. Since theoperating program and the application program are not erased and arestored even when the supply of the power is stopped, the operatingprogram and the application program may be executed without performing adownloading operation, when the power is applied.

The controller 560 may operate a data broadcasting application manager.If a data service is requested by the UI, the data broadcastingapplication manager executes the application program stored in thememory 570, processes the requested data, and provides the data serviceto the user.

FIG. 15 is a view showing an example of the demodulator in thebroadcasting signal receiver according. FIG. 15 shows the component fordecoding the broadcasting signal when the broadcasting signal istransmitted as shown in FIGS. 2 to 6. Hereinafter, the demodulator ofthe present embodiment will be described with reference to FIG. 15.

The broadcasting signal receiver restores a carrier sync signal,restores a frame sync signal and performs channel equalization using theknown data information inserted in the mobile service data period in atransmission system, thereby improving reception capability.

The broadcasting signal receiver includes a VSB demodulator 702, anequalizer 703, a known sequence detector 704, an M-VSB block decoder705, an M-VSB data deformatter 706, a RS frame decoder 707, an M-VSBderandomizer 708, a data deinterleaver 709, a RS decoder 710, a dataderandomizer 711, and a signaling information decoder 712. In FIG. 15,for convenience of description, the M-VSB data deformatter 706, the RSframe decoder 707, and the M-VSB derandomizer 708 are collectivelycalled a mobile service data processor and the data deinterleaver 709,the RS decoder 710 and the data derandomizer 711 are collectively calleda main service data processor.

The VSB demodulator 702 and the known sequence detector 704 receive thesignal of which the frequency is tuned by the tuner and isdown-converted into an intermediate frequency (IF).

The VSB demodulator 702 performs the automatic gain control, therecovery of a carrier and the restoration of a timing in considerationof the VSB method so as to convert the received IF signal to a basebandsignal, and outputs the baseband signal to the equalizer 703 and theknown sequence detector 704.

The equalizer 703 compensates for the distortion on the channel includedin the demodulated signal and outputs the compensated signal to theM-VSB block decoder 705.

At this time, the known sequence detector 704 detects the location ofknown data inserted at the transmitter side from the input/output dataof the VSB demodulator 702, that is, the data before the VSBdemodulation or the data after the demodulation. The known sequencedetector 704 outputs the location information and the symbol sequence ofthe known data generated at the location to the VSB demodulator 702 andthe equalizer 703. The known sequence detector 704 outputs informationfor allowing the M-VSB block decoder 705 to distinguish the mobileservice data, which is subjected to the additional error correctionencoding at the transmitter side, and the main service data, which isnot subjected to the additional error correction encoding, to the M-VSBblock decoder 705. Although the connection state is not shown in FIG.14, the information detected by the known sequence detector 704 can beused in the receiver and can be used in the M-VSB data deformatter 706and the RS frame decoder 707.

The VSB demodulator 702 can improve demodulation capability using theknown data symbol sequence at the time of the restoration of the timingor the recovery of the carrier and the equalizer 703 can improveequalization capability using the known data. The decoded result of theM-VSB block decoder 705 may be fed back to the equalizer 703 so as toimprove the equalization capability.

If the data received from the equalizer 703 is the mobile service datawhich is subjected to the additional error correction encoding and thetrellis encoding at the transmitter side, the M-VSB block decoder 705performs trellis decoding and additional error correction decoding asthe inverse processes of the transmitter side. If the data is the mainservice data which is not subjected to the additional encoding and issubjected to the trellis encoding at the transmitter side, only thetrellis decoding is performed.

The data group decoded by the M-VSB block decoder 705 is input to theM-VSB data deformatter 706 and the main service data packet is input tothe data deinterleaver 709.

If the received data is the main service data, the M-VSB block decoder705 may perform viterbi decoding with respect to the received data andoutput a hard decision value or a soft decision value.

If the received data is the mobile service data, the M-VSB block decoder705 outputs the hard decision value or the soft decision value withrespect to the received mobile service data. If the received data is themobile service data, the M-VSB block decoder 705 decodes the data whichis encoded by the M-VSB block processor and the trellis encoder of thetransmission system. In this case, the RS frame encoder of the M-VSBpreprocessor of the transmitter side may become an outer code and theM-VSB block processor and the trellis encoder may become an inner code.The decoder of the inner code may output the soft decision value suchthat the capability of the outer code can be maximized at the time ofthe decoding of the concatenated code.

Accordingly, the M-VSB block decoder 705 may output the hard decisionvalue with respect to the mobile service data and preferably may outputthe soft decision value if necessary.

The data deinterleaver 709, the RS decoder 710 and the derandomizer 711receive and process the main service data. The data deinterleaver 709deinterleaves the main service data output from the M-VSB block decoder705 as the inverse process of the data interleaver of the transmitterside and outputs the deinterleaved data to the RS decoder 710.

The RS decoder 710 performs systematic RS decoding with respect to thedeinterleaved data and outputs the decoded data to the derandomizer 711.The derandomizer 711 receives the output of the RS decoder 710,generates the same pseudo random byte as the randomizer of thetransmitter, performs a bitwise exclusive OR (XOR) with respect to thepseudo random byte, inserts the MPEG sync data in front of every packet,and outputs 188-byte main service data in the packet units.

The data output from the M-VSB block decoder 705 to the M-VSB datadeformatter 706 has a data group form. At this time, since the M-VSBdata deformatter 706 already knows the configuration of the receiveddata group, it is possible to distinguish the mobile service data andthe signaling information having the system information within the datagroup. The signaling information indicates information for deliveringthe system information and can deliver the information on thetransmission parameter including the identifier of the cell.

The mobile service data is output to the RS frame decoder 707 and theM-VSB data deformatter 706 removes the known data inserted into the datagroup and the main service data, the trellis initialization data, theMPEG header and the RS parity added in the RS encoder/non-systematic RSencoder or the non-systematic RS encoder of the transmission system andoutputs the mobile service data to the RS frame decoder 707.

That is, the RS frame decoder 707 receives only the mobile service datawhich is subjected to the RS encoding and/or CRC-encoding, from theM-VSB data deformatter 706.

The RS frame decoder 707 performs the inverse process of the RS frameencoder of the transmission system, corrects errors in the RS frame,adds a 1-byte MPEG sync signal which is removed in the RS frame encodingprocess to the error-corrected mobile service data packet, and the addedmobile service data to the M-VSB derandomizer 708.

The M-VSB derandomizer 708 performs the derandomizing processcorresponding to the inverse process of the M-VSB randomizer of thetransmission system with respect to the received mobile service data andoutputs the derandomized data, thereby obtaining the mobile service datatransmitted from the transmission system.

The signaling information decoder 712 may decode the signalinginformation included in the received signal. FIG. 15 shows an example ofdecoding the signaling information including the identifier of the cellfrom the M-VSB data deformatter 706 or the equalizer 703 according tothe location of the signal carried in the signaling information.

FIG. 16 is a view showing a broadcasting signal receiver according toanother embodiment.

The broadcasting signal receiver according to the present embodimentfurther includes a second memory 620 for storing a program and a memorycontroller 610 for controlling the second memory 620, in addition to thememory 570 of the broadcasting signal receiver shown in FIG. 14.

The broadcasting service data demultiplexed by the demultiplexer 530 maybe decoded by the decoder 540 and may be output and may be input to orread from the second memory 620 by the memory controller 610 forcontrolling the second memory 620. The demultiplexer 530 may store themain service data or the mobile service data demodulated by thedemodulator 520 in the second memory 620.

The controller 560 may control an instant recording function, areservation recording function, and a time shift function of thebroadcasting service data demultiplexed by the demultiplexer 530 throughthe memory controller 610. The controller 560 may reproduce thebroadcasting service data which is already stored in the second memory620 through the memory controller 610 and the demultiplexer 530.

The second memory 620 may be divided into a temporary storage area forstoring the data according to the time shift and a permanent storagearea for permanently storing the data according to the selection of theuser.

The memory controller 610 may control a play function, a fast forwardfunction, a rewind function, a slow motion function and an instantreplay function of the data stored in the second memory 620 according tothe control signal of the controller 560. Here, the instant replayfunction is a function for repeatedly viewing a desired scene. The datawhich is currently being received in real time as well as the data whichis previously stored can be instantly replayed in conjunction with thetime shift function.

The memory controller 610 may scramble and store the received data inorder to prevent the unauthorized copy of the data stored in the secondmemory 620. In contrast, the memory controller 610 may read, descrambleand store the data which is scrambled and stored in the second memory620.

If the broadcasting data for data broadcasting is included in the mainservice data or the mobile service data, the program table informationdecoder 580 may decode the broadcasting data. The data for databroadcasting may be decoded by the program table information decoder 580and may be stored in a data storage unit 630.

If the controller 560 operates a data broadcasting application accordingto the request of the user, the program table information decoder 580decodes the broadcasting data for data broadcasting and outputs thedecoded broadcasting data. The application operated by the controller560 may implement the data broadcasting output from the program tableinformation decoder 580 and output it to the output unit 550.

The program table information decoder 580 may decode, for example, theservice information such as DVB-SI or the broadcasting data according tothe PSI or the PSIP. The broadcasting data for data broadcasting may beof a packetized elementary stream type or a section type. That is, thedata for data broadcasting includes PES type data or section type data.

For example, the data for data broadcasting is included in a digitalstorage media-command and control (DSM-CC) section and the DSM-CCsection may be composed of the TS packet based on 188-byte units. Theidentifier of the TS packet included in the DSM-CC section is includedin the program table information which is a data service table (DST). Ifthe DST is transmitted, 0x95 is allocated as the value of a stream_typefield in the service location descriptor of the PMT or the VCT. Thebroadcasting signal receiver determines that the data for databroadcasting is received if the value of the stream-type field of thePMT or the VCT is 0x95. The data for data broadcasting may betransmitted by a data carousel method.

In order to process the data for data broadcasting, the demultiplexer530 may perform section filtering under the control of the program tableinformation decoder 580, discard the overlapping section, and output thenon-overlapping section to the program table information decoder 580.The program table information decoder 580 can determine whether the datafor data broadcasting included in the broadcasting signal is receivedaccording to the PID of the VCT. The PID of the VCT may be set in an MGTand have a fixed value.

The demultiplexer 530 may output only an application information table(AIT) to the program table information decoder 580 through the sectionfiltering. The AIT includes information on an application executed onthe broadcasting signal receiver, for the data service.

The AIT may include the information on the application, for example, thename of the application, the version of the application, the priority ofthe application, the ID of the application, the status of theapplication (auto-start, operability of the user, kill or the like), thetype of the application (Java or HTML), the class of the application,the location of the stream including a data file, the base directory ofthe application, and the location of the icon of the application.Accordingly, information necessary for executing the application may bestored in the data storage unit 630 using the above-describedinformation.

The application executed by the controller 560 may be received togetherwith the broadcasting data and may be updated. A data broadcastingapplication manager which is executed in order to allow the controller560 to execute the application may include a platform for executing anapplication program. The platform may be, for example, the Java virtualmachine for executing the Java program.

If it is assumed that the data broadcasting service is a trafficinformation service, the broadcasting signal receiver can provide theservice to the users through at least one of characters, voice,graphics, still images, moving images or the like although an electronicmap or a global positioning system (GPS) module is not mounted. If thebroadcasting signal receiver includes the GPS module, the databroadcasting application may be implemented after the GPS moduleextracts current location information (longitude, latitude, andaltitude) received from a satellite. The data storage unit 630 of thebroadcasting signal receiver 630 may store the electronic map includinginformation on links and nodes and a variety of graphic information.

FIG. 17 is a view showing a broadcasting signal receiver according toanother embodiment. Hereinafter, the operation of the broadcastingsignal receiver according to the present embodiment will be describedwith reference to FIG. 17.

The broadcasting signal receiver according to the present embodimentfurther includes a second memory 620 for storing a program and a memorycontroller 610 for controlling the second memory 620, in addition to thememory 570 of the broadcasting signal receiver shown in FIG. 14.

The broadcasting service data demultiplexed by the demultiplexer 530 maybe decoded by the decoder 540 and may be output and may be input to orread from the second memory 620 by the memory controller 610 forcontrolling the second memory 620. The demultiplexer 530 may store themain service data or the mobile service data demodulated by thedemodulator 520 in the second memory 620.

The controller 560 may control an instant recording function, areservation recording function, and a time shift function of thebroadcasting service data demultiplexed by the demultiplexer 530 throughthe memory controller 610. The controller 560 may reproduce thebroadcasting service data which is already stored in the second memory620 through the memory controller 610 and the demultiplexer 530.

The second memory 620 may be divided into a temporary storage area forstoring the data according to the time shift and a permanent storagearea for permanently storing the data according to the selection of theuser.

The memory controller 610 may control a play function, a fast forwardfunction, a rewind function, a slow motion function and an instantreplay function of the data stored in the second memory 620 according tothe control signal of the controller 560. Here, the instant replayfunction is a function for repeatedly viewing a desired scene. The datawhich is currently being received in real time as well as the data whichis previously stored can be instantly replayed in conjunction with thetime shift function.

The memory controller 610 may scramble and store the received data inorder to prevent the unauthorized copy of the data stored in the secondmemory 620. In contrast, the memory controller 610 may read, descrambleand store the data which is scrambled and stored in the second memory620.

If the broadcasting data for data broadcasting is included in the mainservice data or the mobile service data, the program table informationdecoder 580 may decode the broadcasting data. The data for databroadcasting may be decoded by the program table information decoder 580and may be stored in a data storage unit 630.

If the controller 560 operates a data broadcasting application accordingto the request of the user, the program table information decoder 580decodes the broadcasting data for data broadcasting and outputs thedecoded broadcasting data. The application operated by the controller560 may implement the data broadcasting output from the program tableinformation decoder 580 and output it to the output unit 550.

The program table information decoder 580 may decode, for example, theservice information such as DVB-SI or the broadcasting data according tothe PSI or the PSIP. The broadcasting data for data broadcasting may beof a packetized elementary stream type or a section type. That is, thedata for data broadcasting includes PES type data or section type data.

For example, the data for data broadcasting is included in a digitalstorage media-command and control (DSM-CC) section and the DSM-CCsection may be composed of the TS packet based on 188-byte units. Theidentifier of the TS packet included in the DSM-CC section is includedin the program table information which is a data service table (DST). Ifthe DST is transmitted, 0x95 is allocated as the value of a stream_typefield in the service location descriptor of the PMT or the VCT. Thebroadcasting signal receiver determines that the data for databroadcasting is received if the value of the stream-type field of thePMT or the VCT is 0x95. The data for data broadcasting may betransmitted by a data carousel method.

In order to process the data for data broadcasting, the demultiplexer530 may perform section filtering under the control of the program tableinformation decoder 580, discard the overlapping section, and output thenon-overlapping section to the program table information decoder 580.The program table information decoder 580 can determine whether the datafor data broadcasting included in the broadcasting signal is receivedaccording to the PID of the VCT. The PID of the VCT may be set in an MGTand have a fixed value.

The demultiplexer 530 may output only an application information table(AIT) to the program table information decoder 580 through the sectionfiltering. The AIT includes information on an application executed onthe broadcasting signal receiver, for the data service.

The AIT may include the information on the application, for example, thename of the application, the version of the application, the priority ofthe application, the ID of the application, the status of theapplication (auto-start, operability of the user, kill or the like), thetype of the application (Java or HTML), the class of the application,the location of the stream including a data file, the base directory ofthe application, and the location of the icon of the application.Accordingly, information necessary for executing the application may bestored in the data storage unit 630 using the above-describedinformation.

The application executed by the controller 560 may be received togetherwith the broadcasting data and may be updated. A data broadcastingapplication manager which is executed in order to allow the controller560 to execute the application may include a platform for executing anapplication program. The platform may be, for example, the Java virtualmachine for executing the Java program.

If it is assumed that the data broadcasting service is a trafficinformation service, the broadcasting signal receiver can provide theservice to the users through at least one of characters, voice,graphics, still images, moving images or the like although an electronicmap or a global positioning system (GPS) module is not mounted. If thebroadcasting signal receiver includes the GPS module, the databroadcasting application may be implemented after the GPS moduleextracts current location information (longitude, latitude, andaltitude) received from a satellite. The data storage unit 630 of thebroadcasting signal receiver 630 may store the electronic map includinginformation on links and nodes and a variety of graphic information.

FIG. 18 is a view showing a broadcasting signal receiver according toanother embodiment. The broadcasting signal receiver according to thepresent embodiment will be described with reference to FIG. 18. Thebroadcasting signal receiver includes a tuner 510, a demodulator 520, ademultiplexer 530, an IP filter 535, a decoder 540, an output unit 550,a controller 560, a memory 570 and a program table information decoder580. The operations of the components of the broadcasting signalreceiver shown in FIG. 18, which are equal to those of FIG. 14.

For example, the controller 560 may determines whether the cell whichreceives the broadcasting signal is changed, from the program tableinformation decoded by the program table information decoder 580, forexample, the MGT, and obtain the cell ID if the cell is changed.Alternatively, the controller may determine whether the handover occursfrom the power of the signal received by the tuner 510 and obtain thecell ID from the MGT received from the cell.

The controller 560 may obtain the channel information for transmittingthe same broadcasting contents as the broadcasting contents which arereceived from the previous cell, from the program table informationdecoded by the program table information decoder 580, for example, theCIT. The channel information is the channel information of thebroadcasting data identified by the broadcasting stream identifier ineach cell.

The controller 560 may control the tuner 510 to tune the channelinformation of the changed cell and control the demodulator 520, thedemultiplexer 530 and the decoder 540 to process the broadcasting signalof the tuned channel.

In the example shown in FIG. 18, the demultiplexer 530 may demultiplexthe IP stream in addition to the video/audio stream and the programtable information from the demodulated signal. If the IP stream isincluded in a private section of the MPEG-2 TS and is transmitted, thedemultiplexer 530 outputs the private section including the IP stream tothe program table information decoder 580. The program table informationdecoder 580 may decode the private section and output the IP stream tothe IP filter 535. Alternatively, if the IP stream is not included inthe private section and an IP datagram is included directly indemodulated stream, the demultiplexer 530 may demultiplexes the IPdatagram from the demodulated signal and output the demultiplexed IPdatagram to the IP filter 535.

The IP filter 535 may selectively output the IP stream selected by theuser according to the control signal of the controller 560.Alternatively, the IP filter 535 filters the IP datagram including theemergency alert message regardless of the selection of the user andoutputs it to the controller 560, when the emergency alert message isincluded in the IP datagram.

The output IP stream may be output to the decoder 540 and thevideo/audio information included in the IP stream may be output from theoutput unit 550. The IP stream may include the first program informationand the second program information. Accordingly, if the emergency alertmessage is included in the IP datagram, the emergency alert message maybe output on the output unit.

The data handler 561 may process and output the data broadcasting signalincluding the emergency alert message transmitted by the IP datagramfrom the IP filter 535. The middleware engine 563 controls theenvironment of the broadcasting reception system such that the databroadcasting signal is output and processes and outputs the databroadcasting signal through the output unit 550 together with thevideo/audio data.

A data handler 561 may process and output the data broadcasting signaltransmitted from the IP filter 535 by the IP datagram, and a middlewareengine 563 controls the environment of the broadcasting receiving systemso as to the broadcasting data and processes and outputs thebroadcasting data together with the video/audio data output from theoutput unit 550.

The effects of the broadcasting signal receiver and the method fortransmitting/receiving the broadcasting signal are as follows.

First, the cell can be identified in the MFN environment and thus themobile reception of the broadcasting signal is possible. Second, abroadcasting system for mobile reception compatible with a broadcastingsystem for fixed reception can be provided. Third, although the usermoves to an area in which the broadcasting signal is transmitted with adifferent frequency in the MFN environment, the same broadcastingprogram can be conveniently viewed without tuning the channel.

FIG. 19 is a flowchart illustrating a method for processing an emergencyalert message.

When the emergency alert message is received, the broadcasting receiverdetermines whether the received emergency alert message is equal to theemergency alert message which is most recently received (S1400).

If it is determined that the currently received emergency alert messageis equal to the previously received emergency alert message in the stepS1400, then the currently received emergency alert message is notprocessed and is discarded.

If it is determined that the currently received emergency alert messageis not equal to the previously received emergency alert message in thestep S1400, then it is checked whether the emergency alert messagerequires the forced change of the channel to the emergency alert channel(S1410).

If it is checked that the emergency alert message does not require theforced change of the channel in the step S1410, then the receivedemergency alert message is processed according to the value of the“alert_priority” field (S1480).

If it is checked that the emergency alert message requires the forcedchange of the channel in the step S1410, then the channel is changed tothe emergency alert channel according to the channel information of theemergency alert channel included in the EAT (S1420).

The broadcasting receiver receives and displays the broadcasting signalof the emergency alert channel on the screen (S1430). If the emergencyis not cancelled (S1440), then it is checked whether the broadcastingreceiver moves to another cell while the broadcasting signal of theemergency alert channel is displayed on the screen (S1450). When theintensity of the received broadcasting signal weakens or the version ofthe program table information managed by the MGT is changed, it isdetermined that the cell is changed.

If it is checked that the broadcasting receiver moves to another cell inthe step S1450, then the emergency alert broadcasting signal iscontinuously displayed on the screen using the emergency alert channelinformation of the changed cell included in the EAT (S1460). When it ischecked that the cell is changed, the cell ID can be obtained. The cellID may be obtained by parsing the MGT or the EAT or may be obtained fromthe signaling information of the received signal.

If it is checked that the broadcasting receiver does not move to anothercell in the step S1450, then the broadcasting signal of the emergencyalert channel is continuously displayed on the screen (S1430).

If the emergency is cancelled (S1440), then the channel is returned tothe previous channel before tuning to the emergency alert channel(S1470).

If the broadcasting receiver does not move to another cell, then thechannel is returned to the previous channel using the channelinformation of the previous channel stored in the broadcasting receiver.

When the broadcasting receiver moves to another cell, the channel isreturned to the previous channel using the channel information of thecells, the cell ID of the current cell and the channel information ofthe previous channel stored in the broadcasting receiver.

As described above, in a method for processing an emergency alertbroadcasting signal, a data structure, and a broadcasting receiveraccording to the present invention, it is possible to continuouslyprovide a service such as an emergency alert message even in a receptionsystem for receiving a broadcasting signal while moving.

It will be apparent to those skilled in the art that variousmodifications and variations can be made in the present inventionwithout departing from the spirit or scope of the invention. Thus, it isintended that the present invention covers the modifications andvariations of this invention provided they come within the scope of theappended claims and their equivalents.

What is claimed:
 1. A method of transmitting a broadcast signal in atransmitter, the method comprising: encoding mobile data for additionalforward error correction (FEC); forming data groups of the encodedmobile data, each formed data group including the encoded mobile data,signaling information and a plurality of known data sequences, whereinat least two of the plurality of known data sequences have differentlengths, and wherein placeholders for the main data, an MPEG-2 headerheaders and non-systematic Reed-Solomon (RS) first parity data areinserted in each formed data group; de-interleaving data in the formeddata groups; removing the placeholder for the main data andnon-systematic RS first parity data in the de-interleaved data of thedata groups; replacing the placeholder for the MPEG-2 header headerswith the MPEG-2 headers in the de-interleaved data of the data groups;outputting mobile data packets including the replaced MPEG-2 headers anddata in the data groups in which the placeholder for the main data andfirst parity data are removed; multiplexing main data packets includingthe main data with the output mobile data packets; performing systematicRS encoding on the main data in the multiplexed data packets; performingnon-systematic RS encoding on the mobile data in the multiplexed datapackets; and transmitting the broadcast signal including the systematicRS encoded main data and the non-systematic RS encoded mobile data. 2.The method of claim 1, wherein the mobile data includes a cellinformation table (CIT) having including information indicating a numberof transmitters transmitting the mobile data.
 3. The method of claim 2,wherein the CIT further includes information indicating an area in whichat least one of the transmitters is located.
 4. The method of claim 1,further comprising: trellis encoding the systematic RS encoded main dataand non-systematic RS encoded mobile data in a trellis encoder, whereina memory included in the trellis encoder is initialized at a start ofeach of the plurality of known data sequences.
 5. The method of claim 4,further comprising: re-calculating RScalculating second parity data ofmobile data packets having changed data during initialization of thememory.
 6. An apparatus for transmitting a broadcast signal, theapparatus comprising: a frame encoder configured to encode mobile datafor additional forward error correction (FEC); a group formatterconfigured to form data groups of the encoded mobile data, each formeddata group including the encoded mobile data, signaling information anda plurality of known data sequences, wherein at least two of theplurality of known data sequences have different lengths, and whereinplaceholders for main data, an MPEG-2 header headers and non-systematicReed-Solomon (RS) first parity data are inserted in each formed datagroup; a de-interleaver configured to de-interleave data in the formeddata groups; a packet formatter configured to remove the placeholder forthe main data and non-systematic RS first parity data in thede-interleaved data of the data groups, replace the placeholder for theMPEG-2 header with the MPEG-2 headers in the deinterleaved data andoutput mobile data packets including the replaced MPEG-2 headers in thedeinterleaved data of the data groups and to data in the data groups inwhich the placeholder for the main data and first parity data areremoved; a multiplexer configured to multiplex main data packetsincluding the main data with the output mobile data packets; an firstencoder configured to perform systematic RS encoding on the main data inthe multiplexed data packets and perform non-systematic RS encoding onthe mobile data in the multiplexed data packets; and a transmission unitconfigured to transmit the broadcast signal including the systematic RSencoded main data and the non-systematic RS encoded mobile data.
 7. Theapparatus of claim 6, wherein the mobile data includes a cellinformation table (CIT) having including information indicating a numberof transmitters transmitting the mobile data.
 8. The apparatus of claim7, wherein the CIT further includes information indicating an area inwhich at least one of the transmitters is located.
 9. The apparatus ofclaim 6, further comprising: a trellis encoder configured to trellisencode the systematic RS encoded main data and non-systematic RS encodedmobile data, wherein a memory included in the trellis encoder isinitialized at a start of each of the plurality of known data sequences.10. The apparatus of claim 6, the apparatus further comprising: a secondencoder configured to re-calculate RS second parity data of mobile datapackets having changed data during initialization of the memory.